Since different antennas and devices have different RF properties, I'm going to go ahead and say that unless your beacons/devices are identical to each other, then no, you should not expect the same RSSI reading, even if their locations are identical. This is because the device cannot know how much power is in an RF signal before it passes through its circuitry, and better and bigger antennas will transmit/receive better than crappier ones.
That said, RSSI values of 0 will be read as 0 with both devices, and also maximum RSSI values, assuming that the two devices use the same RSSI scale, which doesn't seem to have to be the case, as wikipedia says: "As an example, Cisco Systems cards have a RSSI_Max value of 100 and will report 101 different power levels, where the RSSI value is 0 to 100. Another popular Wi-Fi chipset is made by Atheros. An Atheros based card will return an RSSI value of 0 to 127 (0x7f) with 128 (0x80) indicating an invalid value."
Anyway, if your devices are identical, then I would expect the readings to be identical as well, or at least very close to each other.